The faceless and gender-neutral computerised dancing figures were then shown to 155 of the dancers' peers, none of whom was able to recognise the individual they were watching and so were not influenced by appearance or familiarity.

The symmetry of the dancers was assessed by matching their elbows, wrists, knees, ankles, feet, ears, and third, fourth and fifth fingers.

And the result was a resounding victory for symmetrical men and women over their asymmetrical peers.

The best dancers are the most symmetrical

Not only did women overwhelmingly prefer dances performed by symmetrical men, but men preferred dances by symmetrical women, although the link was not as strong.

"In species where fathers invest less than mothers in their offspring, females tend to be more selective in mate choice and males therefore invest more in courtship display," says Brown.

"Our results with human subjects correlate with that expectation. More symmetrical men put on a better show, and women notice."

The researchers say there was a significant interaction between symmetry, sex, and dance ability.

"Symmetrical males were evaluated as significantly better dancers than asymmetrical males, accounting for 48% of the variance in dance ability.

"Even though symmetrical females were significantly better dancers than asymmetrical females, female symmetry only accounted for 23% of dance ability," they add.

But they stopped short of saying why symmetry was so crucial and said further research was necessary.

"Attractive dances may be more difficult to perform, more rhythmic, more energetic, more energy efficient, or any combination of these factors," they say.

"Does dance ability correlate with reproductive success? We plan to address this question with long-term data from the same population."